Question 18.58

28. Consider which uses more energy: your house— with heating, cooling, electric, and perhaps gas for cooking—or the cars in the household (say, 2). A common measure of energy is 1 BOE, one barrel of oil equivalent, the approximate energy released by burning one barrel of crude oil, for which we have

  1. Suppose that in 1 year, your household uses 7000 kWh of electricity plus 700 therms of natural gas () for heating, and that the household has two cars that get an average of 25 mpg and are each driven 15,000 miles per year. Which uses more energy: your house or the cars?
  2. Recalculate your answer to part (a) to take into account that conversion of natural gas, oil, or coal into electricity is at best only 40% efficient, while natural gas for heating can be about 90% efficient.

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